1. Field of the Invention
The present invention relates to a method for producing lining supports or elongated supporting structural units from a hardening building material and a reinforcement. These parts can be produced on the site by overgound and underground construction, the building material being liquid and brought together with the reinforcement only at the installation site. Lining supports produced using the invention are particularly suitable for mines and tunnel construction as an independent road lining or part of a road lining in which the lining supports act as props or prop pillars for the separately supported (anchored or lined) roof or the exposed rock. Inventive props and prop pillars differ from each other essentially by their slenderness ratio, that is, the ratio of diameter to length. In so far as the invention also relates to the production of elongated beams for overground and underground construction, these beams may be masts such as those used as lantern poles for strong sources of light, chiefly in street lighting. The inventive method may also be used to produce other beams, for example bulkheads.
The man field of application of the invention, however, is in drift mining, and in particular coal and ore mining. More precisely, the invention is useful for the road lining, where the inventive supports are used as a supporting lining in particular in a gate-end road whose roof may be secured by a temporary lining, for example anchored. The invention shall therefore be explained herein chiefly with reference to this field of application.
2. Description of the Prior Art In the main field of application of the invention referred to above, the inventive lining supports replace the pillars employed in particular in pillar-and-chamber work but also in longwall work and used as a supporting lining, and set in single or double rows. In so far as these pillars have been made of wood up to now, they are crosswise and horizontal layers of trimmed timbers. Wooden pillars of this kind are flexible to a certain extent due to their compressibility, which is advantageous in terms of lining technology for avoiding premature destruction of the lining by the rock pressure. While wood is usually, though not always, available and can be processed well, it is generally expensive. Further disadvantages in terms of wooden lining technology are the varying strengths of the timbers cooperating in a pillar, and the lack of lateral stability of the pillars depending on their slenderness ratio. The lack of resistance of wood to moisture and fire also occasionally causes considerable problems. The economy of such pillars is also diminished by the considerable expenses for the transport and processing of the wood and the high labor costs underground for erecting the pillars. By using a hardening building material and a reinforcement, the invention aims at lining supports which, due to their production on site in the drift, are easier to transport and cheaper to erect. In addition, the prop pillars of the present invention do not involve any problems of lateral stability due to their design, and are insensitive to moisture and fire.
Wooden pillars are the oldest known lining supports used in longwall work and pillar-and-chamber work, and there have already been proposals to replace them by pillars made of reinforced concrete. These are mainly concrete ties provided with reinforcing bars, which replace the trimmed timbers. A supporting lining consisting of such pillars involves the disadvantage that it is much heavier than a wooden lining, which considerably aggravates the transport problems and increases the labor costs, so that no advantages can be obtained beyond the possibility of replacing expensive and possibly unavailable wood by an available building material and eliminating the problems of fire resistance and insensitivity to moisture. In addition, however, the transport and erection of the described concrete tie pillars are complicated by the difficulty, based on the reinforcement, that the protruding reinforcing bars constitute a considerable danger of accident. On the one hand, they may cause dangerous injuries; on the other hand, they frequently crop up as unexpected obstacles.
In order to increase the necessary inner strength of the pillars and ease the problems of reinforcement, another known proposal suggests building cylindrical pillars of prefabricated cylindrical plates of steel fiber concrete. These pillars follow the principle of pillars made of concrete ties because the plates are stacked. The production of such prefabricated concrete parts already makes relatively high demands on the material due to the required strengths. Transport is expensive due to the high weight and often involves considerable danger of accident due to protruding steel fibers. The erection of the pillars must take place without setting pressure, so that an individually fitting wooden wedging must be provided between the upper end of the pillar and its contact surface. The labor expended is accordingly high. Nevertheless, the pillars are not always successfully set perpendicular to the stratification. This leads to uneven loads which may destroy this kind of pillar prematurely. The invention aims in particular at a lining support which avoids the dangers existing up to now.
Pull-out or telescoping props have also been proposed to replace wooden pillars. These props have telescopic parts made of relatively cheap material that are locked relative to one another after the prop is pulled out, and then filled with a hardening building material. Such a lining system with props or prop pillars avoids the problems of too little lateral stability of the pillar construction due to its consisting of one piece, but makes special demands on the material used as a filling; since the mixing water remains in the building material as it hardens, the production of such props must proceed relatively slowly. The expense for the telescopic prop part varies depending on the length and diameter of the prop pillar. Thus, of the main advantages of the pull-out prop system, namely the easier transport and low-quality material, are at least partly lost. Due to the lack of strength of cheap materials, the sturdy construction required for prop pillars is not possible.
On the other hand, the invention differs from a complete supporting lining produced underground of the form which supports at least the ends and the roof of a road, is made of fabric tubes extending in the transverse and longitudinal directions of the road but is filled with hardening building material progressively in the longitudinal direction of the road. In this arrangement, the pressure of the pumpable building material is used to obtain the shape and contact of the lining member in question against the rock from the initially slack tube as it is filled with the liquid building material, which presupposes that the proportion of water is retained in the tube. The fabric tube acts only as a shaping dead mold which, due to its waterproofness, greatly delays the hardening of the building material, thereby demanding considerable labor and time and in practice not leading to sufficient early strengths for the lining. It is virtually impossible to reinforce such a lining either, whereby the tube itself is useless after the building material has hardened. By contrast, the present invention aims at the production of a quickly supporting lining member whose load capacity is higher than that of the building material pillar.
Lining members of this kind, which develop high load capacity due to a composite construction, are already known in the form of the above-described pillar design with prefabricated reinforced concrete parts, but could not be produced from building materials in fabric tubes. However, fabric tubes filled with hardening building material are known as auxiliary elements in road lining which, when pumped up with the liquid building material, join the road lining to the surrounding rock by being braced between the segments of the road lining and the lagging and the rock. In this method the expandability of the folded fabric tube inserted into the support section is systematically exploited upwardly and to the side, the tube being provided with a corresponding oversize compared to the cavity in the support section, and stretched by the pumping to form an annular body of irregular cross-section which allows, along its length, for positive closure of the support section and the lagging or bumps in the rock with the tube. The load capacity of such a lining is ultimately based on the extremely expensive steel lining and therefore involves only a small proportion of cheaper materials. In particular, lining members cannot be obtained therefrom in the form of props or prop pillars for roads driven in the seam and longwall work. By contrast, the invention provides a road lining which is not based on any steel lining members but itself has the strength required for props and prop pillars.